The present invention relates to a method and apparatus for producing layered composites of gallium arsenide and silicon, layered articles produced there by and devices produced therefrom.
The III-V compound semiconductor GaAs has a rapidly growing impact on electronic circuits and optoelectronic devices. Thus the control preparation of GaAs films of appreciable technological interest. In general, in order to achieve high-quality epitaxial growth, GaAs films or grown as GaAs wafers, which are rather expensive. On the other in the most important achieve semiconductor silicon is nonstandard substrate for high-quality of gallium arsenide preparations. The GaAs devices prepared on silicon substrates, however, would be considered to increase the flexibility of optoelectronic device structures.
The ability to efficiently effectively layer gallium arsenide on silicon has been the subject of substantial research over the past several decades in light of the wide variety of electrical devices that can be produced from the chemically and physically uniform combination of the materials.
One of the difficulties in combining these two materials is that it has been difficult to layer them together so as to achieve a stoichiometric combination of the two species. This is naturally important to provide reliable and consistent electrical or photoelectrical function in devices made from this combination. This is also important to the ability of such processes to be scaled for production of large amounts of these composites of reproducible quality.
Beyond the challenge of uniform and stoichiometric combination, it is also desirable to be able to create layered composite materials whose smoothness is on the order of nanometers in scale. This is particularly important to the production of electronic circuits and devices that would benefit from these composites, such as rectifiers, as well as photoelectric devices, such as sensors and optoelectronic mutliplexers.
For instance, the combination of the excellent high-frequency electrical properties of the III-V compound semiconductor GaAs with the sophisticated technology of Si has been very attractive for the semiconductor industry since a long time.4 GaAs offers high carrier mobility and fast optoelectronic properties, which are needed for high-frequency devices and laser applications. In order to take full advantage of the GaAs properties an almost perfect crystal structure and very low impurity concentration are required. These top-quality demands increase the price of GaAs devices clearly beyond the cost of Si based devices. The speed of GaAs linked with the meanwhile perfect and rather inexpensive production of Si seems the perfect optoelectronic merge from the technology and economic point of views. In the last few years, several research groups have reported epitaxial growth of thin-film GaAs on Si wafers.14,15 The most frequently applied method to form thin-film GaAs on Si is molecular beam epitaxy (MBE). However, it seems that MBE is eventually not the superior method to conquer the problems of large lattice mismatch (4.1%) and thermal expansion coefficient (2.5 times) between GaAs and Si.1 In this paper, we introduce pulsed-laser deposition (PLD) as a cost-effective alternative method to achieve high-quality GaAs films on Si. We demonstrate that the PLD of GaAs on counter-doped Si forms a functional pn-junction. The device shows novel and appealing features, which are applicable to telecommunication purposes.
Accordingly, the present invention allows one to achieve GaAs/Si composites, such as GaAs films on Si, which are in substantially stoichiometric combination.
The present invention further permits one to prepare layered GaAs/Si composites, such as GaAs films on a Si layer, that are able to reach levels of smoothness on nanometer scale.
In addition to the features mentioned above, objects and advantages of the present invention will be readily apparent upon a reading of the following description and through practice of the present invention.